[HBR] which receiver is THE BEST receiver

[Amargosa Enterprises]

----- Original Message -----
From: "Walter A. Hutchens" <waltah at earthlink.net>

> In replying to Rob you indicated a "no" answer on low drift as follows -
>
>" The Ted Crosby HBR series are an example of a sharp designer doing a
> home brew design for ham construction.   Ease of construction -- YES;
> flexible performance -- YES, adequate sensitivity; freedom from serious
> intermod, enough selectivity, all YES.   Low drift -- NO on low bands;
HELL
> NO on 20 and 10.   Ease of use -- FAIR to NO -- many controls, most were
> built with 'economy' dials.
>
> But it remains a truly great design because that combination of choices
> worked well for U.S. ham skill levels and pocketbooks."

Depending on your personal drift requirement, my experience with
a 20-tube W6TC design differs from your statement as follows -

80 meters, ambient 65 deg F;  temp comp 7.2 pfd N750
cold receiver/cold coil +2.02 kHz drift for 42 minutes to zero beat lock
warm receiver/cold coil +1.07 kHz drift for 20 minutes to zero beat lock
after initial zero beat lock 65 minutes zero drift to receiver shut-down

40 meters, ambient 65 deg F; temp comp 10 pfd N750
cold receiver/cold coil +1.68kHz drift for 44 minutes to zero beat lock
warm receiver/cold coil +0.42 kHz drift for 10 minutes to zero beat lock
after initial zero beat lock 247 minutes zero drift to receiver shut down

20 meters, ambient 64 deg F; temp comp 20 pfd N750
cold receiver/cold coil +1.43 kHz drift for 24 min to zero beat lock
warm receiver/cold coil +0.67 kHz drift for 9 minutes to zero beat lock
after iniitial zero beat lock 187 minutes zero drift to receiver shut down

10 meters, ambient 66 deg F; 17.5 pfd N750
cold receiver/cold coil +4.62 KhZ drift for23 min, -1.22 kHz for 6 min
to zero beat lock]
warm receiver/cold coil +2.5 kHz drift for 14 min, -0.6 kHz for 6 min
to zero beat lock
after initial zero beat lock 125 minutes with 50 Hz wander-and-return to
zero beat to receiver shut down

All test data taken in 1968.  Coils had been extensively tested and
temperature compensated with N750 capacitors; each coil set had
at least a dozen test runs before the final N750 cap size was identified.
The receiver uses the W6TC Hartley oscillator design, is built on a steel
chassis with a 19-in rack mount front panel, cabinet with a fuly
ventilated hinged top, zero backlash in the Eddystone 898 dial and
variable tuning capacitor.

50 Hz wander in 10 meter coil set is symptomatic of air movement (other
than thermal) over the L3 oscillator coil.  My 40-year old notes do not
address whether that condition existed during the test period.

In all cases, test runs ended when I got bored and/or sleepy and shut
things off. No test was run (other than 10 meters) to a point where
zero beat began to drift  beyond initial lock-in.

 From my perspective, as a CW-only operator with little interest in 10
meters, this was acceptable performance.  It is certainly better than my
old Hammarlund Super-pro and certainly falls in the range I remember
for other commercial hot-cathode technology designs.

If cold-start drift is still a problem beyond the limits shown , drift
times can be lessened by storing coils in a warming box kept at
about 80 deg F.  Interior temps in my HBR when fully warmed
up are around 90 deg F, somewhat higher on warm days.  I
suppose the ultimate answer is to leave the HBR tube filaments
turned on continuously; that, unfortunately given difficulty and
cost of replacement tubes, can be an expensive solution.  In
the end, hot-cathode technology is just as stated - hot!

Other than these facts, your advice to Rob was excellent.

73 W6HHT